Shutter assembly



Oct. 13, 1959 A. JQ MANGoLD, JR., ETAL 2,908,254

SHUTTER ASSEMBLY Filed Dec. 2, 1955 2 Sheets-Shet 1 AGENT Oct. '13, 1959 A. .1. MANGoLD, JR., ETAL 2,908,254

' sHuTTER ASSEMBLY 'iled Dec. 2. 1955 l2 sheets-sheet 2 George M. Shero BY/ Mofa/M4. N

Anthony J. Mangold, Jr.

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hielt. are .lixedlyt attached. to shutter. rod'26. Slug .tube isproyided, with an cylindrical. space` in whichshutter le l i 3.4

z :'1 5 rQtl Zlfreelypmoves longitudinally. restricted.. only Yby Anthony J. Mangold@ In., and George M. Ispring.;Q5,32.,. ,S1ug.tuhe;34,is.sealed to-bottomange and Shera, Haiiltoli, Ohio, ssignors to National Lead topangepzzpat point. by ,rfneansE of shoulder 3.7. and igeolnpany NewYork, NX., al corporation of New lthre,adedlpolrjgiorr35k-UQ; bysueh qghgpsuitablfemgans as points 13,",1{Z ;u;icl;2?g` luy-gaskets or other suitable material. v I iV 2 'shows' shutter 24A in the open Orp-withdrawn 'lzhis"inve`ntir.\n relates` to a 'shutter assembly. More 15 position;` When Vthe 'shutter isin the closed or extended specifically, it relates to a magnetically operated, vacuumposition, the semicircular edge of the shutter is in intimate tight shutter assembly for use in vacuum furnaces and contact with surface 25 of the lower recess of top flange the like. 22. Also shown are holes 19 through which pass bolts Satisfactory operation of vacuum melting equipment or other suitable fasteners for attaching the shutter assemrequires periodic visual inspection by the operator who 20 bly to the upper and lower sight tube lian-ges. Bushings must have an unobscured view of the melt to produce 21 are xedly attached in holes 19 in order to provide an uniform results and to obtain necessary operating data. air-tight seal. The usual practice has been to incorporate a sight glass The drawings show how shutter 24 is ixedly attached for this purpose. Present equipment allows particles of to one end of shutter rod 26. Near the other end of superheated metal and slag, thrown up from the melt, to 25 shutter rod Z6, slug 28 is movably mounted. Its motion impinge on the surface of the glass and cause pitting and upon said shutter rod Z6 being limited by stops 30 and 31 obscuring of the surface so as to prevent accurate deterwhich are axed to shutter rod 26. Spring 32 provides mination of temperature by optical means as well as the means by which shutter 24 is kept in the normally visual inspection of the melt. In order to overcome this closed position. This spring is loaded during the opening situation, wipers and similar devices have been employed movement of the shutter.

for removing the metal and slag from the sight glass. In operation, the shutter is normally in the closed or These have been activated by mechanical linkages which, extended position thus protecting the surface of the sight in a short time allow leakage, due to movement through 'glass from fumes, dirt'and occluded metal particles which the seal, and decrease the vacuum. Also the surface of tend to attack the glass and thereby decrease its transthe glass soon becomes so obscured that replacement is parency. When the operator wishes to View the melt he,

necessary and this operation requires that the furnace be by pushbutton or other suitable means, closes the eleci idle during this period. trical circuit which energizes the solenoid. The magnetic An object of this invention, therefore, is to provide a ilux passes through the slug tube, which is composed of shutter assembly which may be employed to prevent the a nonmagnetic metal, to the slug. The magnetic ux accumulation of metal particles and slag on the glass and 40 causes the slug to move toward the more intensive field subsequent pitting of the glass. Another object is to of the magnet. The slug strikes the end stop and as it provide a remotely operated shutter assembly for shieldmoves farther into the field of the magnet, the shutter v ing a sight glass whereby the effective life of the sight is moved into the open or retracted position, its motion glass, as installed, will be materially increased. Still anbeing limited, according to a typical construction, by other object is to provide an integrated, air-tight shutter the contact of the edge of the shutter with the edge of assembly which will insure maintenance of a high degree the recess in which the shutter fits. At the same time, of vacuuminthe melting equipment. the slug is forced against the spring compressing and These and other objects will become apparent from loading it. The shutter is held in the open position as the following more complete description of the invention long as the solenoid is energized by the electric circuit. and the annexed drawings wherein: When the operator has finished viewing the melt, he opens Figure 1 shows a sectional view of the side elevation the electric circuit which denergizes the magnet. At this of a typical shutter assembly for accomplishing the time there is no magnetic flux to hold the slug in the aforementioned objectives. open position so the expanding force of the loaded spring Figure 2 shows a general top view of the apparatus acts against the shutter rod and moves the shutter into presented in Figure 1. its normally closed position.

Referring now to Figure 1, the shutter assembly 14 is By utilizing vacuum melting equipment having the shown in place disposed between lower sight tube flange shutter assembly interposed in the sight tube between 12, which is xedly attached to lower sight tube 10, and the furnace and the sight glass, according to the present upper sight tube flange 16, which is affixed to upper sight invention, the sight .glass is kept free of slag and particles tube .18. More specifically, the shutter assembly consists, of molten metal. Since dirt and metal cannot become in part, of bottom flange 20, the bottom lsurface of which deposited on the glass, to any significant degree, the effechas a projecting shoulder arranged to provide a snug t tive life of each glass is greatly increased which in turn in the recess of lower sight tube flange -12 and which has decreases the down time of the furnace due to sight glass an annular space or view port in the center for viewing replacement.

purposes. Permanently aiixed by suitable means'to the 65 The apparatus of the present invention is simple to bottom flange 20 is top llange 22 which has a circular install and economical to operate and maintain. In addi,- recess in the top surface to accommodate sight glass 38, tion, with'the apparatus of the present invention, a high a substantially rectangular recess in the lower surface to degree of vacuum can be maintained in the furnace since allow the free longitudinal movement of shutter 24 and there are no gland type seals, as generally used prior to an annular space between the two recesses for viewing this invention, to develop leaks.

purposes. To one end of shutter 24 and extending there- While this invention has been described and illustrated from is shutter rod 26. Movably mounted on shutter by the examples shown, it is not intended to be strictly limited thereto and other modiiications and variations may be employed within the scope of the following claim.

We claim: Assembly for protecting the sight glass in) a. vacuum vmelting furnace which comprises a housingadapted for air-tight installation in-a viewing tube, said housingcom- Vprising a viewing section having a view port Vextending therethrough, the upper surface of said viewing section having a recess therein, a sight glass disposedin said recess, a shutter rod housing section sealably joined in an air-tight manner to said viewing section, a shutter receiving recess in the shutter rod housing section, a

shutter assembly within said shutter rod housing section V comprising a slidably movable shutterV disposed in said shutter rod recess, a shutter rod aXed to one end of said shutter and extending therefrom, a pair of stops xedly positioned on the other end of said shutter rod, a slug movably mounted on said shutter rod, between said stops 1 and a spring positioned between the slug and themshutter 'rod housing, saidy spring acting to move said shutter from said shutter rod recess to cover said view port and magnetic activating means comprising a solenoid disposed around the said slug, said magnetic activating means acting to move the shutter from a position covering the view port into the shutter receiving recess.

References Cited in the tile of this patent UNITED STATES PATENS v 910,405 France Jan. 28, 1946 

